District of Columbia Code
Chapter 5 - Estates in Land
§ 42–513. Future estates — Alternative

Two or more future estates may be created to take effect in the alternative, so that if the first in order shall fail to vest the next in succession may be substituted for it and take effect accordingly.
(Mar. 3, 1901, 31 Stat. 1352, ch. 854, § 1026.)
1981 Ed., § 45-213.
1973 Ed., § 45-813.